Television film projector



June 30, 1942. H. R. LUBCKE ETAI.

TELEVISION FILM PROJECTOR Filed July 27, 1940 Patented June 30, 1942UNITED STATES PATENT f OFFICE TELEVISION FILM PROJECTOR `Harry B.Lubcke, Los Angeles, Willet E. Brown, Santa Anita, and William B.`Klein, Los Angeles, Calif., assignors to Don Lee Broadcasting System,Los Angeles, Calif., a corporation of California Application July 21,1940, serial No. 341,900' 1 1 claim. (ci. 11s-1.2)

ond with a two to oneinterlace, so that the picture i'leld is scannedevery sixtieth of a second, with the result that whatever the phaserelationship may be between the motion picture pro-` jector and thetelevision pickup, a change of frame of the film will occur duringcertain of the television scansions if the ordinary type of motionpicture projector be used. The time required for moving the film betweensuccessive frames isabout 14% of the frame period, which equals about tnof a second or 35% of one television scanning period. It will thus beseen that with the standard motion picture projector the frame of theiilm will be changed every two and one-half scansions, resulting in adarkening of the field which lasts for about one-third (35%) ofthescansion.

The present invention is concerned with the storage type of televisionpickup tube, typified by the Iconoscope," wherein the signal generatedby the scanslon of each point of the picture eld is proportional (to arst approximation) to the integral of the light which has fallen on thatpoint since it last was scanned. If the ileld has been dark a portion ofthe time since the last scansion the intensity of the signal will bereduced approximately in proportion to the ratio of the time ofdarkening to the total time between scansions.

The eld at a television receiver is illuminated only one point at atime, each point being illuminated once in each l/o of a second underpresent standards, and this rate is itself slow enough to result in aperceptible flicker.l It ls to avoid this ilicker that interlace" isused, alternate lines being scanned in successive scansions, for it hasbeen found that if the rate of flicker of the held as a whole is doubledit becomes imperceptible, the inter-line flicker not being noticed andthe eye appreciating only an apparent average illumination. If, however,the intensity of signal differs materially for the successive scansions,as

' it will if the ield has been darkened for nlm changing before onescansion but not before the next in the same repetition period, thevalue of the interlace is largely lost, andra flicker of a particularlyannoying type results.

In the past the problem thus presented has been met in two distinct wayseach involving the use of a special type of projector. The first ofthese methods involves displaying successive frames of the lm forunequal intervals, the rst .frame being exposed during three scansionsof the field, while the succeeding frame is exposed during two scansionsonly, thus retaining the same average illm speed but making the changeoi frame occur Veach time in the same epoch of the scanning. The fieldis illuminated brieiiy between the scansions, which take place while thephotosensitive screen is dark.

The second method of solving the problem involves the use of acontinuous projector, wherein the film progresses at a constant ratethrough the projector and the consequent motion of the image isoptically compensated so as to hold it in a xed position on the screen.This method can be used either with the storage type or theinstantaneous type of television pickup, but the projector is expensive,complicated, and must be manufactured with an extremely high degree ofaccuracy in order to be satisfactory.

The method of our invention, as above stated. involves the use of atelevision pickup or camera of the storage type, and among the objectsof the invention to provide a method of transmitting motion pictures bytelevision which is applicable to any desired ratio of nlm frame rate toscanning rate; to provide a method to which standard motion pictureprojectors may be readily adapted; to provide a method which willproduce 'ickerless television images irrespective of the frame andscansion rates employed; and to provide a method which greatly decreasesthe cost and complexity of the equipment used. It is also an object toprovide apparatus whereby the method here set forth may be accomplishedIand to provide apparatus with which direct pickup cameras may be usedfor motion .picture projection with no positional or electricalinversion of the camera.

Our invention possesses numerous other objects and features ofadvantage, some of which, together with the foregoing, will be set forthin the following description of specic apparatus embodyingk andutilizing our novel method. It is therefore to be understood that ourmethod is applicable to other apparatus, and that .we do not limitourselves, in any way, to the apparatus of the present application, aswe may adopt various other apparatus embodiments, utilizing the method,within the scope of the appended claims.

The instant invention operates through the cooperation of two groups offactors. The first group is dependent upon the nature of vision as itaffects the perception of flicker, and in such perception contrast is aprimary factor. Flicker (i. e., visible or apparent iiicker), isincreased if the variation in intensity of one point from instant toinstant is high. It is also increased if the area which is flickering isin immediate proximity to an area which is not, or which is flickeringin opposite phase. Sharp definition of the flickering area thereforeincreases its apparent intensity.

The second group of factors has to do with the operating characteristicsof storage type television pickup tubes. These tubes will operate over adefinite range of operating conditions. When an optical image is focusedupon the sensitive mosaic of the tube the individual droplets or islandsof photosensitive material lose electrons, in the initial instant ofillumination, proportionally to the illumination, thereby acquiringpositive charges. As these charges increase with time the more highlyilluminated portions (and therefore the more positive portions) exhibitspace charge effects to a greater and greater extent, as a result ofwhich the emission decreases, so that they approach a certain limit ofpotential. Added to this is the fact that the more positive pointsattract more strongly any stray electrons which may be in theneighborhood, and this also has the effect of decreasing with time therate at which these points acquire positive charges. The photosensitivemosaic is scanned by a moving beam or pencil of electrons, which has atwofold effect. First, certain of these electrons neutralize thepositive charges which were photoelectrically acquired. Second, there isalso a tendency of the scanning beam to knock off secondary electrons,which causes the particles to tend to swing positive rather thannegative, the magnitude of these effects being dependent upon thevelocity and intensity of the impacting beam and the potential of theelectrodes which pick up the electrons knocked off or emitted byphotoelectric action. The two effects cooperate to drive the variousareas to a definite equilibrium. In practice it is usually the effort tohave the scanning beam bring the points scanned to complete equilibrium.

It is an experimental fact, however, that the degree of neutralizationof charge obtained in scanning is under the control of the operator, i.e., that it is possible by varying the intensity of the scanning beam toneutralize the stored charges more or less completely, leaving more orless of a residual charge having image characteristics upon the screen.Since it is the neutralization of charge that generates the televisionsignal it would appear obvious that the best picture would be obtainablewhen the stored charge was completely neutralized. Again, however, it isan experimental fact that if the scanning beam be gradually increased inintensity from zero, the signal will be found to approach a maximum withthe charge incompletely neutralized, and after this point is reachedrelatively large changes in intensity of the scanning beam causerelatively little change in signal intensity.

Another operating feature of these tubes is the fact that thedegradation of the image due to the limitation of positive charges inthe high lights is reduced by back lighting; i. e., if the 'tioncomprises projecting the motion picture to be transmitted upon thescreen of a storage type television pickup intermittently as with theconventional type of projector, scanning the screen with an electronbeam preferably of minimum vintensity so as to leave a material picturecharge upon the screen, and illuminating the screen during the period ofoccultation of the film by a diffused light which will reduce thecontrast in average illumination between the portion of the picture areawhich is illuminated for the full *frame periodk and that which isscanned after a period of `\oc`cultatlon. Preferably, alsof theoccultation is accomplished so as to cut ofi illumination graduallyinstead of suddenly, making the contrast between those portions whichhave been occulted and those which have not more gradual, and backlighting is also used to increase the effectiveness of the period duringwhich the screen is fully illuminated by the image as will be more fullyset forth later.

From the aspect of apparatus the invention comprises the combinationwith television pickup equipment of the storage type and a motionpicture projector having an intermittent motion for progressing the filmand a shutter for occulting this film during its progression, of meansto supplying to the screen d-uring occultation a general illuminationdistributed over the screen which will maintain the average illuminationof the picture field sensibly constant.

Referring to the drawing:

Fig. 1 is a lschematic diagram, reduced to lowest terms, showing theessential features of a system embodying our invention.

Fig. 2 is a graphical representation showing the relationship existingbetween frame frequency, vertical scanning frequency, repetitionfrequency, and illumination in the system of our invention.

Fig. 3 is a graphical representation of the distribution of illuminationover the picture field where conventional apparatus is used.

Figs. 4 and 5 are diagrammatic representations of two forms of shuttersadapted for use with this invention.

Fig. 6 is a schematic showing of a modification of the apparatus shownin Fig. 1.

In the diagrammatic representation of Fig. 1 the film l is preferablystandard sound-motionpicture film, exposed at the rate of twenty-fourframes per second and bearing upon its edge the customary sound track.The major portionvof the projector may be in any conventional form, andis shown as including the usual feed reel 2 on which the film is storedbefore projection, and from which it is unwound by means of the pulldownsprocket 3, 'to be progressed past the lm gate 4 by a claw or `otherintermittent mechanism 5, and thence passed over the takeupvsprocket 1and through the sound head 9 to be rewound upon the takeup reel l0. Thevarious loops and auxiliary sprockets which are utilized in theconventional projector are used here also, but are not shown since theyare completely conventional and would merely complicate the showing.

The nlm is illuminated by an optical system comprising, for example, alamp I I backed up by a reflector I2, with a condensing lens I3 arrangedin accordancewith the usual practice to focus an image of the filamentthrough'the lm gated into the plane of the optical center of aprojecting lens Id. Instead of the image being projected directly uponthe screen, however, it is inverted deiiected by a first surface mirrorI5 through the shutter I'l and onto the inclined screen I9 of a storagetype television pickup tube 20. The tube is enclosed within aconventional camera housing 2! which is indicated by the dash lines.

The television camera is entirely conventional and with it areassociated the usual deflecting circuits, master pulse and scanninggenerators, etc., but these are not shown as theyare well known to thoseskilled in the art and are merely ancillary to the present invention.

The primary diierence between the setup thus described and thecombination of a standard motion picture projector and a standardtelevision camera lies in the shutter Il. A preferred form of thisshutter is shown in Fig. 4. It differs from the standard shutter in itsscimiter shape, the curved edges being provided to cause occultation ofthe image on the different portions of the screen at slightly differentepochs, so that the transition band between occulted andy nonoccultedfilm will not occur in perfectly straight lines across the image andwill therefore be less apparent to the eye. This is a 4secondaryfeature, however, since the important characteristic is that the shutteris translucent or light diffusing rather than either transparent oropaque. This may be accomplished by making the shutter of transparentplastic (e. g., Lucite) and spraying upon it droplets of transparentplastic or lacquer, which, by forming minute lenses,- alter the focaldistance and diiiuse the image so as to permit substantially the sameamount of light to fall manipulation is necessary in order to transmitupright pictures.

In considering the operation of the device attention rst is directed toFig. 2 which shows the time sequence of the various events in one halfcycle of operation of 'a conventional projector as used with this typeof television camera.

The second half cycle differs from the rst only in that the rst scansiontherein is of even instead oli-odd unes. Abpve the axis is shown themotion picture sequence, whichstarts with the operation of the pull-downmechanism, lasting 14% of the frame period, during whichportion of theperiod the shutter occults the light from the lm. With the ordinary,opaque type of shutter there is Ano illumination of the lrnl for thisoccultation period and hence no storage of image on any part of thescreen. At the end of the pull-down time, the screen is, fullyilluminated and remains so until the next occultation and pull-down 1&4of a second later.

Beneath the axis line is shown the sequence of events in the televisionsystem. i In this case the scanning of the vfield is assumed to havebeen completed at the instant that the pull-down starts, and during thefirst 8% of they scanning period the scanning beam moves from the lowerright-hand corner of the picture field back to the upper left-handcorner of the field and then starts to scan the odd numbered lines ofthe picture eld. When the odd lines have all been scanned the secondscanning period begins, 8% thereof again being occupied by the return ofthe beam, and this time the even numbered lines are scanned.

If the scanning beam has been so adjusted as to neutralize the screencompletely the effective charges start to build up from zero the instanttheV beam has passed, and'continue to build up during the repetition ordouble scanning period. Because the eld was dark during the iirstportion of this period, however, it is only when the double period hasfully been accomplished after the pull-down that the elements aretransmitted at full brilliancy. The relative rate at.

which any point in the iield theoretically acquires its charge isproportional to the slope of curve 2'2, zero during Voccultation andconstant between occultations, the actual rate being proportional also,of course, to the intensity of illumination of the individual point. Thestrength of the signals generated by the scanning of the point at anytime tis similarly proportional to the integral of this slope betweenthe limit.: (t-r) and t, where r is the period of repetition, or l@ of asecond, the curve representing this integral being illustrated by thecurve 23 of Fig. 2, wherein the ordinate at any point representing aninstant t is equal to the ordinate of curve 23 at the point t minus itsordinate at (t-r).

If the successive sections of the curve 23 be superimposed, as shown inFig. 3, it will be seen that the average amount of light falling uponeach part of the screen is the same when inte grated over the completehalf cycle of the two frames or five scanning periods, but that thereare two areas, each occupying about 19% of the effective area of theframe (N1/2% of the total frame period including .the return period)that increase in brightness F11/2% every fth scanning period, or twelvetimes per second, which causes the annoying icker before mentioned.Between these two areas of bad iiicker there are transition areas,occupying the remainder of the tele'- vision frame, in which the ickerchanges phase, vbeing reduced to half the intensity and increased todouble the frequency half way between the two badly flickering areas.

When, now, the translucent or diffusing shutter of our invention issubstituted for the opaque shutter of ordinary practice, the averageillumination remains constant throughout and the visible icker isgreatly reduced.. Some localized iiicker remains. For those portions ofthepicture where illumination is equal to `theaverage the flickerbecomes zero, but the darker portions of the picture will nowbeincreased in brightness during the intervals when they wereformerlyde,- creased, whilev in those portions which are above averagebrightness there will still be van increase operate in addition to thefact that the actual intensity of the flicker has been reduced to aboutone-half in the case of themost widely varying points. In the case ofthe shadows these factors include rst,4 the fact that apparent flickeris a function of brightness, and the less the intrinsic brilliancy theless the apparent icker. 'I'he second is the fact that a short period ofdarkness occurring in a relatively long interval of illiimination isvery much less apparent than the ireverse condition.

In the case of the high lights the favorable factor lies in the pickuptube rather than in the eye of the beholder, and resides in the factthat the charges in the high lmhts tend to approach a limiting value andthat therefore a slight decrease in illumination during a portion of thescanning period has a very slight eifect upon the strength of the signalis approached.

Itshould be bornev in mind that the diffused illumination during thepull-down period covers the entire eld and not any particular part ofthe field. Its eiect therefore is merely to raise slightly the averageillumination of the field as a whole, thereby slightly decreasing thecontrast.

This results only in a slight increase in the D. C. component of thesignalQand since practically all television systems provide for somedegree of manual background control, even where automatic control isalso used, this can readily be compensated for.

While the factors thus far brought out comprise the major step in ourinvention, it may be made even more eiective by further steps, eachconstituting a successive approximation toward the absolute eliminationof flicker. 'I'he second major step in our method comprises theadjustment of the pickup tube so that the scanning beam is at minimumintensity consistent with approximately maximum signal, i. e., so that aresidual image is left upon the screen after each scansion.

Why this should be so may not be apparent.

without a more detailed analysis than is practical here. Qualitatively,however, it may be seen that with the use of the system thus fardescribed those portions ofthe eld which formerly exhibited a flicker inbrilliancy will now exhibit what may be termed a dicker in contrast,displaying the greatest amount of contrast in the course of thosescansions which with the ordinary system would display the greatestdegree of brilliancy. If we assume that one-third of the image strengthis left when the area of greatest contrast is scanned, the next scanningof this area/,will result in a signal wherein two-thirds of the chargehas been acquired at low contrast and one-third has been left at highcontrast, thus increasing the dilerential of contrast of the lowcontrast scansion by one-third. Conversely, when the high contrastportion is next scanned only two-thirds of the charge will have beenacquired at high contrast while the remainder has been acquired at lowcontrast, and the contrast upon this scansion will be correspondingly reduced. It will bevunderstood that these ngures are a first approximationonly, and that the actual increases and decreases in contrast, resultfrom the summation of a geometric series. The effect, however, is totend to equalize the differences in contrast. It' might be expected thatthis would result in ghost images in parts of the eld where motionoccurs, but actually residual flicker can be substantially neutralizedbefore aaeaoce ghosts become apparent. 'Ihe third step in the series ofapproximations has already been mentioned, and comprises so occultingthe ileld, las by means of the curved shutter blade, that the areaswhere icker would normally occur are not marked out by clearly definedstraight' lines,

where this limiting value y which the eye can readily follow. 'Ihat thisactually has the eiect of reducing apparent icker is an empirical factwhich will be left to the psychologists for explanation.

Since it will be apparent that the principal, and in fact the onlyundesirable effect of the system as thus far described is a slightreduction in contrast, it is desirable that the contrast be built up asmuch as possible, and we have found that the loss can be regainedsubstantially in its entirety by the back lighting before referred to.This is accomplished by means of a lamp 25 mounted in the camera behindvthe screen of the pickup tube, where it will illuminate the Walls of thetube without illuminating the screen itself. l

It has been stated above that the illumination of the screen which isused in the elimination of the flicker is the average illumination ofthe picture iield as a` whole. A more accurate statement would be thatthe illumination should be the average apparent illumination asdetermined by the eye. It will be recognized that the shutter I1 beingof a diffusing character and also being a solid body, will have adiierent coeiiicient of refraction from the air in which it isoperating, and there will be some loss of light due to reflection fromits various surfaces, absorption in the passage through it, as well asby its defocusing effect. Experience has shown that this slight decreasein actual illumination below the average is not disadvantageous, in thatthe light which actually reaches the screen usually approaches moreclosely to the occular average than where the absolute averageillumination is the same. Another method of practicing our invention,wherein the amount of icker neutralizing light is under control, is tosubstitute for the shutter Il of Fig. 4 the type shown in Fig. 5. Inthis case shutter Il is also made of transparent material, preferablyplastic, the shading upon the blade indicating a mirror deposit upon thesurface which graduates in opacity and also in reflecting ability fromthe edges of the blade toward the center where the heaviest shading isshown, this portion being completely opaque. A lamp 21, backed by areflector 29 and provide-d with a 1ers so throws a diffused beam of nghty along the path shown by the arrows against the reflecting surface ofthe shutter and thence onto the sensitive screen I9.' 'I'he lamp 21 isshown as being excited by pure D.C., indicated as supplied from abattery 3|, since it is important that no flicker be present in thisillumination, it being understood that any other pure D.C. source may besubstituted for the battery. Intensity of illumination may be adjustedby the rheostat 32. The graduated reflecting and occulting surface ofthe mirror I1 causes the diffuse reflected light from the lamp 30 toincrease in intensity in substantially the same time and the sameproportion that the image is decreased in intensity by the occultingaction of the shutter. As in the case of the curved edges ofthe shutterblades shown in Fig. 4, the gradual occultation makes the transitionfrom occultation to non-occultation and the reverse less distinctlymarked, and thus contributes to the results desired. In this case theamount of icker neutralizing light is under the control of the operator,who adjusts the rheoaaeaoae stat 32 until the best results are obtainedas determined by eye upon a monitor screen.

Fig. 6 indicates a slight modification of the equipment'shown at theright of Fig. 1. In this case the inverting mirror I is omitted, and thepath of the image is direct from the lens I4 (Fig. 1) to the screen I9.In order that the light from the lamp 30' may reach the screen I9, theshutter i'la is mounted at an angle.

In Fig. 6 the pickup tube and the camera are inverted in comparison withthe tube in Fig. 1, to indicate symbolically that in this case, sincethe image is not optically inverted, other means must be used in orderthat the transmission will appear upright.

Various other modications of the mechanical means used to accomplish themethod of this invention will be apparent. It is clear that a large partof the value of the invention may be appreciated even though the shutterI1' be made completely opaque throughout if its surface be reflecting.It will be further apparent that it is not necessary that the shuttercontrol flicker neutralizing illumination, but that this may be done byusing a lamp 30 having an instantaneous luminous response and openingand closing its circuit electrically in synchronism with the shutter.Other possible modifications will doubtless suggest themselves to thoseskilled in the art.

One of these possibilities deserves particular mention, however, andthat is the total elimination of the shutter. 'The movement of the filmin itself destroys the image, and tends to distribute the illuminationuniformly over the screen. With certain types ofy picture, e. g., inpictures where the whole of one side of the field is materiallydifferent in illumination from the other, this method may give evenbetter results than those heretofore discussed, since the average istaken for individual strips of the film, rather than for the whole. Inother situations,

however, it may result in streaks in the reproduced picture, andtherefore it is not our present preference. The fact that it vis usableat all, however, leads to the obvious conclusion that it is notessential that the shutter occult the image for the entire pull-downtime and experiment has shown that this is the case, and that, ifdesired, the shutter which may be of any of the types here discussed,may be made to occult the image, for, say 10% instead of 14% of thepull-down time without introducing perceptible streaks or travel ghosts.

It will also be apparent that the various modiiications shown may becombined. Thus the shutter of Fig. 4 may be used and additional il- Klumination supplied to the screen from the separate source 30, thenon-specular reflection from such source onto the screen making up anydeficiency in the average illumination caused by reflection from andabsorption in the shutter of the light from the film.

In the final analysis we have found that so far as the eye can detectthe method and apparatus as here described result in completeelimination of flicker. Examination of the screen under a magnifyingglass reveals some residual iiicker, just as the inter-line fiicker canbe thus detected even when direct pickup is used. For practicalpurposes, however, it is entirely satisfactory, and is not only simplerand less expensive than conventional methods, but is less difficult ofadjustment, and being applicable to any ratio of frame frequency toscanning frequency, is more flexible.

We claim:

1. The method of television transmission from motion picture film with apickup device having a photosensitive screen ofthe charge-storing typewhich comprises the steps of progressing said film intermittently,projecting stationary images of successive frames of said film onto saidscreen during substantially the whole intervals between suchprogressions, and illuminating said screen during the periods ofmovement of said film with substantially the same quantity of light ascomprises said images but having different distribution over said screenthan the light projected thereon during the image projecting intervals.

2. The method of television transmission from motion picture film with apickup device having a photosensitive screen of the charge-storing typewhich comprises the steps of progressing said film intermittently,projecting stationary images of successive frames of said film onto saidscreen during substantially the whole intervals 'between saidprogressions, continuing to project illumination from said film ontosaid screen during the periods of progression, and destroying the imagecharacteristics of said illumination during said periods.

3. The methodr of television transmission from motion picture film witha pickup device having a photosensitive screenl of the charge-storingtype which comprises the steps of `progressing said film intermittently,projecting light through said film and onto said screen, focusing saidlight as an image of a portion of said film upon said screen duringsubstantially the whole intervals between such progressions, graduallydestroying said focus immediately before the period of progression ofsaid film, and gradually restoring said focus at the end of said period.

4. The method of television transmission from motion picture film with apickup device having a photosensitive screen of the charge-storing typewhich comprises the steps of progressing 1 said film intermittently,projecting light through said film and onto said screen, focusing saidlight as an image of a portion of said film upon said screen duringsubstantially the whole intervals between such progressions, graduallydecreasing the intensity of said image immediately before the period ofprogression, and maintaining the total illumination of said filmsubstantially constant by general illumination increasing in intensty asthe intensity of said image decreases.

5. The method of television transmission'from motion picture film with apickup device having a photosensitive screen of the charge-storing typewhich comprises the steps of progressing said nlm intermittently,projecting stationary images of successive frames of said film onto saidscreen during substantially the whole intervals between suchprogressions, occulting said imagesat intervals, such occultationoccurring non-rectilinearly across said screen and during the periods ofprogression of said film, and illuminating said screen generally duringthe periods of said occultation with a quantity of light substantiallyequal to that forming said images. i

6. In the method as set forth in claim 1, the additional step ofscanning said sensitive screen with an electron beam, said beam being ofsufficient intensity to remove only partially the.

charges stored by the projection of light thereon.

7. In the method as set forth in claim 1, the step of occulting saidimages from said screen during said periods of progression, separatelygenerating light during said periods, and illuminating said screengenerally with said separately generated light during said periods.

8. llihe method as set forth in claim 1 including the step ofilluminating separately the portions of said pickup device adjacent saidscreen while preventing said illumination from reaching said screen.

9. Television apparatus for the transmission of signals from motionpicture film comprising a motion picture projector including means forintermittently progressing a film therethrough, means for illuminatingsaid iilm during substantially the whole intervals between suchprogressions, a projection lens for forming an image of the illuminatedportion of said film, and means for simultaneously destroying said imageand for illuminating the plane thereof with substantially the sameamount of light differently distributed during the periods ofprogression of said film.

10. Television apparatus for the transmission of signals from motionpicture film comprising a motion picture projector including means forintermittently progressing a film therethrough, means for illuminatingsaid illm during substantially the whole intervals between suchprogressions, a pickup device of the charge-storing type. a projectionlens for forming an image of the illuminated portion of said film uponthe photosensitive screen of said pickup device, and a semi-transparentshutter timed with said intermittent means for destroying the imagecharacteristics of the illumination from said Projection lens reachingthe plane of said'image during the periods of progression of said lm.

11. Television apparatus for the transmission of signals from motionpicture film comprising a motion picture projector including means forintermittently progressing a film therethrough, means for illuminatingsaid film during substantially the whole intervals between suchprogressions, a pickup device of the charge-storing type, a projectionlens for forming an image of the illuminated portion of said film uponthe photosensitive screen of said pickup device, and a shutter oftransparent material having a. light diffusing surface timed with saidintermittent means for destroying the image characteristics of theillumination reaching the plane of said guage during the periods ofprogression of said i2. Television apparatus for the transmission oisignals from motion picture film comprising a motion picture projectorincluding means for intermittently progressing a film therethrough,means for illuminating said lm during substantially the whole intervalsbetween such progressions, a projection lens for forming an image of theilluminated portion of said film, a shutter of transparent material andhaving a mirror surface of graduated opacity increasing from the edgesoi' said shutter to the center thereof, said intermittent meansocculting said image during the periods of progression of said film, aseparate source of light, and means for directing light from said sourceonto said surface at an angle such as to be reflected therefrom onto theplane of said image.

13. Apparatus in accordance with claim 9 including means for invertingthe image produced by said projection lens.

14. The combination as set forth in claim 9 including a shutter forocculting said image during the periods of progression of said film, a

separate source of illumination, and means timed with said shutter fordirecting illumination from said source onto the plane of said imageduring the periods of occultation only.

l5. In combination, a motion picture projector having intermittent meansfor progressing a film therethrough, means for illuminating a portion ofsaid film during substantially the whole intervals between suchprogressions and a projecting lens for forming an image of saidilluminatedportion, a television pickup having a photosensitive screenof storage type positioned in the plane of said image, separate meansfor illuminating said pickup with the exception of said screen, and ashutter on said projector timed in synchronism with said intermittentmeans, said shutter being formed of transparent material and having alight diffusing surface.

16. Apparatus in accordance with claim 15 wherein said shutter comprisesa rotating blade having non-radial edges.

17. Apparatus in accordance with claim 15 wherein said shutter comprisesa rotating scimiter-shaped blade.

HARRY R. LUBCKE. 'WILLET H. BROWN. WILLIAM S. KLEIN.

